Jaw Shrinks With Age, 40-Year Study Finds

WEDNESDAY Nov. 9, 2011 -- The human jaw shrinks with age and that can result in crowded front teeth among the elderly, a new study has found.

Swedish researchers looked at plaster molds made of the jaws of dental students in 1949 when the students were in their 20s, and follow-up jaw molds of the same people made in 1959 and 1989.

"We found that over these 40 years there was less and less room for teeth in the jaw," Lars Bondemark, a professor of orthodontics at Malmo University, said in a university news release.

This reduced amount of space for front teeth was the result of a few millimeters of shrinkage in both the length and width of the jaws, primarily the lower jaw.

The amount of jaw shrinkage varies between individuals and is influenced by hereditary and anatomical factors. In some cases, the changes are significant enough that people notice a change in their bite.

"In that case it's good to know that this is normal," Bondemark said.

Dentists need to consider the continuous shrinkage of jaws when they plan major work on a patient's bite.

"We're working against nature, and it's hard to construct something that is completely stable," Bondemark said.

And, he added, "We can also eliminate wisdom teeth as the cause, because even people who have no wisdom teeth have crowded front teeth."